IntermediateSITUATIONAL
Imagine a new feature request arrives but adding it will increase build and test times significantly, slowing other developers. How would you evaluate trade-offs and implement a solution that balances fast iteration with code quality?
Software Engineer
General

Sample Answer

On a recent team of 8 we faced a feature that doubled CI times from 10 to 22 minutes. I first measured where time went and prioritized: unit tests ran fast, integration and end-to-end (E2E) tests were the culprit. I proposed splitting test suites and gate commits on fast checks while running full E2E pipelines asynchronously. We added build caching, parallelized jobs, and implemented incremental CI that runs only impacted test subsets—this cut perceived feedback to ~4 minutes for 80% of commits, while nightly full-suite runs and pre-merge E2E for release branches preserved quality. We used feature flags to merge early without exposing unstable code. Within a month we reduced team idle time by ~60% and kept our defect rate stable at ~0.5 bugs/1000 LOC.

Keywords

Measure CI bottlenecks and prioritize fixesSplit fast vs slow tests with incremental and parallel executionUse feature flags and asynchronous full-suite runs to enable fast iteration